That's not even what I'm getting at.
Ignoring the fact that if someone is going to knife you, you are going to get knifed.
Unless you are going to carry one of those monstrously huge machete half-breeds around with you
(Which is REAALLLLY illegal, like everywhere but Oregon),
or some other very dangerous weapon with considerable reach, you're going to get ganged.

Forget the fact that you have a folder, forget the fact that you've trained for years.
3+ people descend upon you with weapons, unless you are the badass of the century
(and some people are, but many are not)
you're going to be just another blood stain.

This is all barring guns of course, I am talking Melee.
I was responding to the person talking about "multiple opponent effectiveness." As far as weapon training goes, that's a dream to chase.
The best weapon you have in that situation (again not considering guns) is the fear that no one in the group coming down on you wants to risk getting within range of your blade, so they just leave you alone.

Even then, odds are slim that you will come out on top. Long distance sprinting is your best bet, and I hate to have to say this, because it's been said like eighty billion times.